import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 666
 * Date: 2023-02-22
 * Time: 16:22
 */
public class test {
    public static void main(String[] args) {
        Scanner qqq=new Scanner(System.in);
         String str=qqq.nextLine();
         int arr[]=new int[10000];
         String str1[]=str.split(" ");
         for (int i=0; i<str1.length;i++){
             arr[Integer.parseInt(str1[i])]++;
         }
        for (int i = 0; i < str1.length ; i++) {
            if(arr[i]>1){
                System.out.println("yes");
                return;
            }

        }
        System.out.println("no");
    }
}
